total parenteral nutrition
TRANSCRIPT
TOTAL PARENTERAL NUTRITION
MODERATORS:DR. R S TONK
DR. T R KHURANADR. SARIT CHATTERJEE
Definition of nutrition
• Nutrition (also called nourishment or aliment) is the provision, to cells and organisms, of the materials necessary (in the form of food) to support life.
Types of nutrition
Enteral Nutrition (Definition)
• Nutritional support via placement through the nose, esophagus, stomach, or intestines (duodenum or jejunum)—Tube feedings—Must have functioning GI tract—IF THE GUT WORKS, USE IT!—Exhaust all oral diet methods first.
Parenteral Nutrition (Definition)
• Components are in elemental or “pre-digested” form– Protein as amino acids– CHO as dextrose– Fat as lipid emulsion– Electrolytes, vitamins and minerals
Indications
Conditions that often require nutrition support
Parenteral Nutrition (Types)
• Delivery of nutrients intravenously, e.g. via the bloodstream.– Central Parenteral Nutrition: often called
Total Parenteral Nutrition (TPN); delivered into a central vein
– Peripheral Parenteral Nutrition (PPN): delivered into a smaller or peripheral vein
A.S.P.E.N. Nutrition Support Practice Manual, 2nd edition, 2005, p. 97
Evidence for PN (ASPEN)• When Specialized Nutrition Support (SNS) is
indicated, EN should generally be used in preference to PN. (B)
• When SNS is indicated, PN should be used when the gastrointestinal tract is not functional or cannot be accessed and in patients who cannot be adequately nourished by oral diets or EN. (B)
• The anticipated duration of PN should be >7 days
ASPEN Board of Directors. JPEN 26;19SA, 2002.; ASPEN Nutrition Support Practice Manual, 2005, p. 108
Common Indications for PN• Patient has failed EN with appropriate tube
placement• Severe acute pancreatitis • Severe short bowel syndrome • Mesenteric ischemia• Paralytic ileus• Small bowel obstruction• GI fistula unless enteral access can be placed
distal to the fistula or where volume of output warrants trial of EN
Adapted from Mirtallo in ASPEN, The Science and Practice of Nutrition Support: A Case-Based Core Curriculum. 2001.
Contraindications• Functional and accessible GI tract• Patient is taking oral diet• Prognosis does not warrant aggressive nutrition
support (terminally ill)• Risk exceeds benefit• Patient expected to meet needs within 14 days
Enteral nutrition
Considerations in Enteral Nutrition
1. Applicable2. Site placement3. Formula selection4. Nutritional/medical requirements5. Rate and method of delivery6. Tolerance
Enteral Access: Clinical Considerations
• Duration of tube feeding—Nasogastric or nasoenteric tube for short term—Gastrostomy and jejunostomy tubes for long term
• Placement of tube—Gastric—Small bowel
Placement Site
• Access (medical status)• Location (radiographic confirmation)• Duration• Tube measurements and durability• Adequacy of GI functioning
Enteral Tube Placement
Formula SelectionThe suitability of a feeding formula should be evaluated based on
Functional status of GI tract Physical characteristics of formula (osmolality, fiber
content, caloric density, viscosity) Macronutrient ratios Digestion and absorption capability of patient Specific metabolic needs Contribution of the feeding to fluid and electrolyte
needs or restriction Cost effectiveness
Parenteral nutrition
PN Central Access• May be delivered via femoral lines, internal
jugular lines, and subclavian vein catheters in the hospital setting
• Peripherally inserted central catheters (PICC) are inserted via the cephalic and basilic veins
• Central access required for infusions that are toxic to small veins due to medication, pH, osmolarity, and volume
Venous Sites for Access to the Superior Vena Cava
PICC Lines (peripherally inserted central catheter)
• PICC lines may be used in ambulatory settings or for long term therapy
• Used for delivery of medication as well as PN• Inserted in the cephalic, basilic, median basilic, or
median cephalic veins and threaded into the superior vena cava
• Can remain in place for up to 1 year with proper maintenance and without complications
PN: Peripheral Access
PN may be administered via peripheral access when
• Therapy is expected to be short term (10-14 days)
• Energy and protein needs are moderate• Formulation osmolarity is <600-900 mOsm/L• Fluid restriction is not necessary
A.S.P.E.N. Nutrition Support Practice Manual, 2005; p. 94
Parenteral Nutrition
Macronutrients &Micronutrients
Macronutrients: Carbohydrate• Source: Monohydrous dextrose• Properties: Nitrogen sparing
Energy source3.4 Kcal/gHyperosmolar
• Recommended intake:2 – 5 mg/kg/min50-65% of total calories
Macronutrients: Carbohydrate
Potential Adverse Effects:• Increased minute ventilation• Increased CO2 production• Increased RQ• Increased O2 consumption• Lipogenesis and liver problems• Hyperglycemia
Macronutrients: Amino Acids• Source: Crystalline amino acids—
standard or specialty• Properties: 4.0 Kcal/g
EAA 40–50%, NEAA 50- 60%Glutamine / Cysteine
• Recommended intake:0.8-2.0 g/kg/day15-20% of total calories
Macronutrients: Amino Acids
Potential Adverse Effects:
• Increased renal solute load
• Azotemia
Macronutrients: Amino Acids
• Specialized Amino Acid SolutionsBranched chain amino acids (BCAA)Essential amino acids (EAA)
• Not shown to improve patient outcome• More expensive than standard solutions
Macronutrients: Lipid• Source: Safflower and/or soybean oil• Properties: Long chain triglycerides
Isotonic or hypotonicStabilized emulsions 10 Kcals/g Prevents essential fatty acid deficiency
• Recommended intake: 0.5 – 1.5 g/kg/day (not >2 g/kg)12 – 24 hour infusion rate
Macronutrients: Lipids
Requirements• 4% to 10% kcals given as lipid meets EFA
requirements; or 2% to 4% kcals given as linoleic acid
• Generally 500 mL of 10% fat emulsion given two times weekly or 500 mL of 20% lipids given once weekly will prevent EFAD
• Usual range 25% to 35% of total kcals• Max. 60% of kcal or 2 g fat/kg
Macronutrients: Lipids
Potential Adverse Effects:• Egg allergy• Hypertriglyceridemia• Decreased cell-mediated immunity (limit to <1
g/kg/day in critically ill immunosuppressed patients)
• Abnormal LFTs
Parenteral Base Solutions• Carbohydrate– Available in concentrations from 5% to 70%– D30, D50 and D70 used for manual mixing
• Amino acids– Available in 3, 3.5, 5, 7, 8.5, 10, 15, 20% solutions– 8.5% and 10% generally used for manual mixing
• Fat– 10% emulsions = 1.1 kcal/ml– 20% emulsions = 2 kcal/ml– 30% emulsions = 3 kcal/ml (used only in mixing TNA, not for direct venous delivery)
The A.S.P.E.N. Nutrition Support Practice Manual, 2nd edition, 2005, p. 97; Barber et al. In ASPEN, The Science and Practice of Nutrition Support: A Case-Based Core Curriculum. 2001.
Other Requirements• Fluid—30 to 50 ml/kg (1.5 to 3
L/day)– Sterile water is added to PN admixture
to meet fluid requirements• Electrolytes– Use acetate or chloride forms to
manage metabolic acidosis or alkalosis• Vitamins: multivitamin formulations• Trace elements
Electrolytes/Vitamins/Trace Elements
• Because parenterally-administered vitamins and trace elements do not go through digestion/absorption, recommendations are lower than DRIs
• Salt forms of electrolytes can affect acid-base balance
Parenteral Nutrition Vitamin Guidelines
Vitamin FDA Guidelines*
A IU 3300 IU
D IU 200 IU
E IU 10 IU
K mcg 150 mcg
C mg 200
Folate mcg 600
Niacin mg 40
Vitamin FDA Guidelines*
B2 mg 3.6
B1 mg 6
B6 mg 6
B12 mg 5.0
Biotin mcg 60
B5 dexpanthenol mg
15
*Federal Register 66(77): April 20, 2000
Daily Electrolyte Requirements Adult PN
Electrolyte PN Equiv RDA
Standard Intake
Calcium 10 mEq 10-15 mEqMagnesium 10 mEq 8-20 mEqPhosphate 30 mmol 20-40 mmolSodium N/A 1-2 mEq/kg + replacementPotassium N/A 1-2 mEq/kgAcetate N/A As needed for acid-baseChloride N/A As needed for acid-base
ASPEN: Safe practices for parenteral nutrition formulations. JPEN 22(2) 49, 1998
PN Contaminants• Components of PN formulations have been found to be contaminated with trace elements
• Most common contaminants are aluminum and manganese
• Aluminum toxicity a problem in pts with renal compromise on long-term PN and in infants and neonates
• Can cause osteopenia in long term adult PN patients ASPEN Nutrition Support Practice Manual 2005; p. 109
PN Contaminants
• FDA requires disclosure of aluminum content of PN components
• Safe intake of aluminum in PN is set at 5 mcg/kg/day
PN Contaminants
• Manganese toxicity has been reported in long term home PN patients
• May lead to neurological symptoms• Manganese concentrations of 8 to 22
mcg/daily volume have been reported in formulations with no added manganese
• May need to switch to single-unit trace elements that don’t include manganese
ASPEN Nutrition Support Practice Manual 2005; p. 98-99
Calculating Nutrient Needs• Provide adequate calories so protein is
not used as an energy source• Avoid excess kcal (>35 kcal/kg) • Determine energy and protein needs
using usual methods (kcals/kg, Ireton-Jones 1992, Harris-Benedict)
• Use specific PN dosing guides for electrolytes, vitamins, and minerals
Peripheral Parenteral Nutrition
• New catheters allow longer support via this method
• In adults, requires large fluid volumes to deliver adequate nutrition support (2.5-3L)
• May be appropriate in mild to moderate malnutrition (<2000 kcal required or <14 days)
• More commonly used in infants and children• Controversial
Contraindications to Peripheral Parenteral Nutrition
• Significant malnutrition• Severe metabolic stress• Large nutrition or electrolyte needs (potassium
is a strong vascular irritant)• Fluid restriction• Need for prolonged PN (>2 weeks)• Renal or liver compromise
From Mirtallo. In ASPEN, The Science and Practice of Nutrition Support: A Case-Based Core Curriculum. 2001, 222.
Compounding Methods
• Total nutrient admixture (TNA) or 3-in-1– Dextrose, amino acids, lipid, additives are
mixed together in one container– Lipid is provided as part of the PN mixture on a
daily basis and becomes an important energy substrate
• 2-in-1 solution of dextrose, amino acids, additives – Typically compounded in 1-liter bags– Lipid is delivered as piggyback daily or
intermittently as a source of EFA
Two-in-One PN
Advantages of TNA• Decreased nursing time• Decreased risk of touch contamination• Decreased pharmacy prep time• Cost savings• Easier administration in home PN• Better fat utilization in slow, continuous
infusion of fat• Physiological balance of macronutrients
Disadvantages of TNA
• Diminished stability and compatibility• IVFE (IV fat emulsions) limits the amount of nutrients that can be compounded
• Limited visual inspection of TNA; reduced ability to detect precipitates
ASPEN Nutrition Support Practice Manual 2005; p. 98-99
PN Compounding Machines: Automix
PN Compounding Machines: Micromix
PN Solution Components Central Peripheral ---Solutions--- Solutions Lipid- Dextrose- based basedDextrose 14.5% 35.0% <10.0%
Amino Acids 5.5% 5.0% <4.25%
Fat 5.0% 250 ml/ 3.0 - 8.0% 20% fat Courtesy of Marian, MJ.
Initiation of PN• Adults should be hemodynamically stable,
able to tolerate the fluid volume necessary to deliver significant support, and have central venous access
• If central access is not available, PPN should be considered (more commonly used in neonatal and peds population)
• Start slowly(1 L 1st day; 2 L 2nd day)
ASPEN Nutrition Support Practice Manual 2005; p. 98-99
Initiation of PN: formulation• As protein associated with few metabolic
side effects, maximum amount of protein can be given on the first day, up to 60-70 grams/liter
• Maximum CHO given first day 150-200 g/day or a 15-20% final dextrose concentration
• In pts with glucose intolerance, 100-150 g dextrose or 10-15% glucose concentration may be given initially
ASPEN Nutrition Support Practice Manual 2005; p. 98-99
Initiation of PN: Formulation
• Dextrose content of PN can be increased if capillary blood glucose levels are consistently <180 mg/dL
• IVFE in PN can be increased if triglycerides are <400 mg/dL
ASPEN Nutrition Support Practice Manual 2005; p. 109
PN Administration:Transition to Enteral Feedings in Adults
• Controversial• In adults receiving oral or enteral nutrition
sufficient to maintain blood glucose, no need to taper PN
• Reduce rate by half every 1 to 2 hrsor switch to 10% dextrose IV) may prevent rebound hypoglycemia (not necessary in PPN)
• Monitor blood glucose levels 30-60 minutes after cessation
PN Administration:Transition to Enteral Feedings in Pediatrics
• Generally tapered more slowly than in adults as oral or enteral feedings are introduced and advanced
• Generally PN is continued until 75-80% of energy needs are met enterally
ASPEN Nutrition Support Practice Manual 2005; p. 109
Medications That May Be Added to Total Nutrient Admixture (TNA)
• Phytonadione• Selenium• Zinc chloride• Levocarnitine• Insulin
• Metoclopromide• Ranitidine• Sodium iodide• Heparin• Octreotide
Parenteral Nutrition
Infusion Schedules
Infusion Schedules
• Continuous PN Non-interrupted infusion of a PN solution over 24 hours via a central or peripheral venous access
Continuous PN
Advantages• Well tolerated by most patients• Requires less manipulation–decreased nursing time–decreased potential for “touch”
contamination
Continuous PN
Disadvantages• Persistent anabolic state– altered insulin : glucagon ratios– increased lipid storage by the liver
• Reduces mobility in ambulatory patients
Infusion Schedules• Cyclic PN– The intermittent administration of PN via a
central or peripheral venous access, usually over a period of 12 – 18 hours
– Patients on continuous therapy may be converted to cyclic PN over 24-48 hours
Cyclic PN• Advantages–Approximates normal physiology of
intermittent feeding–Maintains:•Nitrogen balance•Visceral proteins
– Ideal for ambulatory patients•Allows normal activity• Improves quality of life
Cyclic PN• Disadvantages– Incorporation of N2 into muscle stores may
be suboptimal•Nutrients administered when patient is
less active–Not tolerated by critically ill patients–Requires more nursing manipulation• Increased potential for touch
contamination• Increased nursing time
Home TPN
• Patient selection–Reasonable life expectancy–Demonstrates motivation, competence,
compliance–Home environment conducive to sterile
technique
Home TPN
• Safety and efficacydepends on:–Proper selection of patients–Adequate discharge planning/education–Home monitoring protocols
Home TPN: Discharge Planning
• Determination whether patient meets payer criteria for PN; completion of CMN forms
• Identification of home care provider and DME supplier
• Identification of monitoring team for home• Conversion of 24-hour infusion schedule to
cyclic infusion with monitoring of patient response
Home TPN
Cost effective–Quicker discharge from hospital– Improved rehabilitation in the home–Reduced hospital readmissions
EN vs PN in Critical Care • If the critically ill ICU patient is
hemodynamically stable with a functional GI tract, then EN is recommended over PN.
• Patients who received EN experienced less septic morbidity and fewer infectious complications than patients who received PN. Strong, Conditional
ADA Evidence Analysis Library, accessed 8/07
EN vs PN in Critical Care
• In the critically ill patient, EN is associated with significant cost savings when compared to PN. There is insufficient evidence to draw conclusions about the impact of EN or PN on LOS and mortality. Strong, Conditional
ADA Evidence Analysis Library, accessed 8/07